Question

The smallest set A such that A ∪ {1, 2} = {1, 2, 3, 5, 9} is?

(a) {2,3,5}

(b) {1, 2, 5, 9}

(c) {3, 5, 9}

(d) None of the mentioned

I have been asked this question in an interview for job.

Question is from Relations in section Compiler Introduction of Compiler

Answer 1

Correct option is (c) {3, 5, 9}

Easy explanation: Given A ∪ {1, 2} = {1, 2, 3, 5, 9}. Hence A = {3,5,9}.